Newsgroups: sci.space.shuttle
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Space Shuttle Cargo
Message-ID: <1989Oct21.033804.3767@utzoo.uucp>
Organization: U of Toronto Zoology
References: <9396@pyr.gatech.EDU>
Date: Sat, 21 Oct 89 03:38:04 GMT

In article <9396@pyr.gatech.EDU> ken@pyr.gatech.edu.gatech.edu (Ken Hall) writes:
>Can anyone tell me whether the plutonium-257 aboard the last flight occurs
>naturally in the earth or if it's synthetic?

Well, it's plutonium 238, actually.  And no, it's entirely synthetic.
Very small traces of plutonium 239 do occur in nature, in uranium ores --
transmuted from uranium naturally, in the same way that it's done in
reactors.  The amounts are much too small to be of practical interest,
though.  The natural production rate is miniscule, and the half-life is
short by geological standards.  There might be a few atoms of natural
plutonium 238 on Earth somewhere, in uranium or thorium ore, but its
half-life is so short that there wouldn't be any detectable amount.
-- 
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry henry@zoo.toronto.edu